import React from 'react'; // react的核心库
import ReactDOM from 'react-dom';
import './index.css';
import App from './App';
import reportWebVitals from './reportWebVitals';
// index.js是react项目的入口文件
ReactDOM.render(
  // App组件是默认渲染的组件
  <React.StrictMode>
    <App /> 
  </React.StrictMode>,
  document.getElementById('root') // react项目的挂载点
);

// If you want to start measuring performance in your app, pass a function
// to log results (for example: reportWebVitals(console.log))
// or send to an analytics endpoint. Learn more: https://bit.ly/CRA-vitals
reportWebVitals();
